Luteinizing hormone increases the abundance of various transcripts, independently of the androgens, in the rat prostate

Epididymal phenotype in luteinizing hormone receptor knockout animals and its response to testosterone replacement therapy

Previous studies reported that epididymis contains functional LH receptors. The LH receptor knockout mice, which have epididymal phenotypes, gave us an opportunity to test the hypothesis that testosterone replacement alone may not be sufficient to reverse phenotypes to wild-type epididymis. The morphological phenotype in knockout animals includes a decrease in luminal diameter of the proximal and distal caput and cauda epididymis, the absence of clear and halo cells in the epithelial lining, a decrease in the height of principal cells and the number of cells containing cilia, a decrease in cilia length, and a change from basal to central location of nuclei in the principal cells. The biochemical phenotype includes a decrease in periodic acid-Schiff reaction product, reflecting the glycogen and glycoprotein synthesis and secretion, a decrease in androgen receptor (AR) and estrogen receptor (ER)beta, and an increase in ERalpha levels. Twenty-one-day testosterone replacement therapy in 30-day-old knockout animals reversed some, but not all, morphological and biochemical phenotypes. Those that did not reverse include luminal diameters of proximal and distal caput and cauda epididymis, the percentage of ciliated principal cells in caput epididymis, and nuclear AR localization. In summary, while our results reaffirm that androgens are important for normal epididymal morphology and function, they indicate that LH could be required for certain facets of epididymal morphology and/or function.

Effects of pituitary hormones on the prostate

BACKGROUND

Although essential, androgens alone are not sufficient to induce normal growth and functionality of the prostate. Nonandrogenic hormones must also be involved in the proliferation of the prostate cancer cells which do not respond to antiandrogenic therapy and which thus become androgen-independent. Prolactin, but also growth hormone and luteinizing hormone, are potentially able to act on both normal and abnormal prostatic cells.

METHODS

In this review we summarize data from the literature concerning the physiological and pathological implications of prolactin, growth hormone, and luteinizing hormone on the prostate.

RESULTS

In rodent prostates, prolactin and growth hormone can induce a variety of effects independently of androgens (e.g., transactivation of certain genes, or synthesis of the major secretion products). Moreover, hyperprolactinemia is responsible for inflammation and dysplasia of the gland, while growth hormone promotes the development of prostate tumors in vivo in the mouse and rat. Growth hormone acts on the gland directly, through prostatic growth hormone receptors, and/or indirectly via the stimulation of insulin-like growth factor-I (IGF-I) synthesis in the liver. Luteinizing hormone receptor is expressed in rat and human prostates. Luteinizing hormone increases the amount of various transcripts in the rat prostate through an androgen-independent pathway.

CONCLUSIONS

Prolactin, growth hormone, and luteinizing hormone, alone or synergistically with androgens, play physiologically significant roles in the normal prostate. The involvement of these hormones in the development of benign prostatic hyperplasia and prostatic carcinoma is an issue that needs to be addressed.